I don't know.
I think Athiesm is a belief. Not a lack of one.
An Athiest believe's there is no God,
Without evidence to the contrary.
So it is a belief.
You speak of a specific type of atheism, Thana, not of atheism in general.
Like theists, atheists come in different flavors: strong and weak, positive, negative explicit, implicit, practical, agnostic, theoretical, &c. If you want to indicate a specific type of atheist you add an adjective. With no adjective it's understood you're speaking of atheism in its basic meaning only: a non belief in God.
Essential atheism isn't a concept, it isn't a stance, it's not the rejection of an idea. True, in certain contexts it may be moot or meaningless, but in some it's a meaningful distinction. It may be meaningless to call a gerbil or a baby illiterate, but they are. The term applies.
Babies are born without language and without a belief in God. They may be neurologically wired for these, but they still must be acquired.